Maybe Leaving SET for Solid State because I want bass

@atmasphere 

"I repaired an SET recently that made 12 Watts. When I tested power bandwidth, I found that it hit a wall at 90Hz. Below that its maximum output power without excess distortion dropped; at 20Hz it could only make 1 Watt."

If this amps output power at 20Hz is one watt then you could assume it's a one watt amp and 20Hz is the bottom of it's power bandwidth. If the THD exceeds 1% at 20Hz and up the frequency scale to 20Khz, its probably even less which would be perfectly in keeping with an SET using a single 300B output tube. Consumers see tubes amps with a rated output of X watts @ 1Khz and think they have a powerhouse when in reality when you consider power bandwidth over the range of human hearing the actual output is barely a fraction of what they're hoping it is. Just tubes.

If this amps output power at 20Hz is one watt then you could assume it's a one watt amp and 20Hz is the bottom of it's power bandwidth.

@faustuss  That would be a lot (most) of SET products!

Most SETs have their power rating at a point where you can see the sine wave on an oscilloscope clearing being distorted. That’s a lot more than just 1% which is an arbitrary value. So I would not fault an SET that could make the same power at 20Hz as it can at 1KHz, but the only SETs that can do that are either parafeed or use the Berning ZOTL output circuit, which uses an air core output transformer. 

Since its the bass where most of musical energy exists, IMO its important for the amplifier to be able to make full power in that region. Our OTLs can make full power to 2Hz, which nicely solves the usual increase in distortion you see with almost any transformer coupled tube amp. 

These days though there are class D amps that are just as smooth in teh mids and highs as the best tube amps and don’t have any bandwidth issues. But some people really can’t get their head around that so here we are :)

Cut off the demand & effort of those lower frequencies from your single ended triode amplifier. Let the SET focus on what it does best. 

You could try something like the analog Sublime Acoustic (no affiliation) as a crossover or low pass filter...running dual subwoofers. Or any other type device out there that can cut off the lower frequencies from your amp without degrading the signal.

You could go on the journey of building your own sub or subs to specifically match your situation. Use a minidsp type device or Dirac just for the sub work & be blown away by the deep linear bass in phase with your mids & highs. 

Trying out & buying a new amplifier is certainly exciting. Also very rewarding if you are able to achieve what you are looking for without having to add subs..& having to put in the effort of dialing them in. 

@dmdalton 

You. Mentioned buying AS class D amps.

Do that!

While not quite as “magical” as a great SET, they have superb bass and overall surpass all but very expensive amps. I loved mine and only replaced them with a $45K Dartzeel integrated. I don’t think you can find any better amp for anywhere near their price.

Ralph has frequently said that his Class D are equal to any of his great tube amps.

I think they are better.

You may want to try the Pass XA-25….I have the XA-25 and the Sit-4, neither sound lean at all the XA25 gives me a tad more bass with my Volti Lucera speakers but I prefer the Sit-4 …the bass is very close…